Litter box with abrasive surface

ABSTRACT

A litter box for domestic cats or other domestic mammals has interior surfaces which are abrasive and that dull the claws of a cat when it uses the litter box. Abrasive material may be incorporated into the surfaces of the box, can be sprayed or rolled on the surfaces or can take the form of a thin flexible sheet of abrasive sheet material which is adhered to the surfaces of the box. Sheets are constructed to fit the side surfaces, end surfaces and bottom surface. The sheets can be adhered with a permanent or with an easily removable adhesive. The easily removable sheets can be replaced when worn. The sheets may include waterproofing material and or scented material and may be imprinted with a design pattern.

This application is a continuation-in-part of application Ser. No.08/209,955, filed Mar. 10, 1994,

FIELD OF THE INVENTION

This invention relates to litter boxes for litter bearing mammals, suchas cats and rabbits, and more particularly to a litter box having anabrasive interior surface to dull the claws of pets, such as cats orrabbits.

BACKGROUND OF THE INVENTION

Domestic house cats are the favorite pet of families in the UnitedStates. Their number is in excess of approximately 67 million. A cat hasremarkable grace, agility and a faultless sense of balance. To a greatextent, this is due to its ingeniously designed, retractable claws thatallow it to establish footing for walking, running, springing, climbingor stretching. The problem with domestic cats is that they love toscratch with their claws, damaging furniture and surfaces in homes andapartments. Domestic cats, unlike cats in the wild, do not have theability to wear their claws down from their razor sharpness throughcontact with the earth and other rough surfaces. The surroundings fordomestic cats do not permit them to frequently come in contact withrock-hard surfaces, soils or trees. Instead, the cats' claws arecushioned by carpet, linoleum and upholstered furniture. Because thesesoft surfaces do not wear down the cats' claws, cat owners sufferserious scratches on the skin and significant furniture damage.

Cat owners who reside in rental properties such as apartments and homesare constantly aware of the damage that can be done by a cat's claws.They can damage not only individuals but also their surroundings as wellas furniture. Cats like to exercise by grabbing surfaces with theirclaws. A solution to the damage caused by the sharp claws of domesticcats is to have the claws surgically removed, have the muscles cut(tendonectomy) or to trim them on a regular basis (approximately fourtimes per month). The American and National Humane Societies, amongothers, consider removal of the claws and tendonectomy to be inhumaneacts. Scratching and clawing are inherent in cats. Removal of the clawscreates an imbalance that can lead to physical injury and topsychological damage. The physical effect of de-clawing is gradualweakening of the muscles of the legs, shoulders and back and balance isimpaired. Emotionally, cats feel defenseless and thus live in a constantstate of stress, making them more prone to disease. It is clear thatde-clawing, while effective, is inhumane and is considered by many catowners to be an uneducated and unacceptable choice.

Another alternative is to trim or manicure the cat's claws on a regularbasis. This is costly and time consuming and often requires a skilledanimal handler or a veterinarian to do the job. Improper trimming of theclaws is painful and can result in harm to the cat. Inexperienced catowners who attempt to trim their cat's claws often trim them tooseverely and cause bleeding and severe pain for the cat.

Scratching posts are available which allow a cat to exercise it's clawsharmlessly. These are merely carpeted poles and thus do nothing tolessen the sharpness of the claws. Cat owners wish to train their catsto use the scratching post instead of the furniture to exercise theirclaws, but are seldom successful.

While the discussion has been specifically directed to domestic cats, itis to be understood that a similar problem exists with otherdomesticated mammals, such as rabbits and ferrets, which are kept aspets in the home.

What is needed to solve this problem is something that a domestic cat orother domesticated mammal will frequently come into contact with whichwill wear down the claws or nails, thus dulling their sharpness andlimit the damage done by the claws or nails. It would also beadvantageous for the claws or nails to be worn down automatically whilethe cat or other mammal is going through it's normal daily routine inthe home environment.

OBJECTS OF THE INVENTION

It is an object of the invention to provide a means by which a domesticmammal will automatically and painlessly wear down it's claws or nails.

It is another object of the invention to provide an abrasive surface forlitter boxes that dulls the claws of a cat when it uses the litter box.

It is another object of the invention to provide a claw dulling surfacefor cat litter boxes.

It is another object of the invention to provide a litter box which hasclaw dulling abrasive interior surfaces.

It is a further object of the invention to provide an easily replaceableclaw dulling abrasive surface on the interior of a cat litter box.

It is yet another object of the invention to provide an abrasive claw ornail dulling surface which can be readily applied to an existing litterbox.

BRIEF DESCRIPTION OF THE INVENTION

Cats create waste on the average of three to five times per day. Mostare trained by their owners to use a litter box. The litter box isfilled with a scented absorbing material that allows the cat to buryit's waste. During burial of the waste, cats use their claws in ascratching motion to move the litter material and their claws come intoscratching contact with the side and or bottom of the litter box. Thisis an excellent opportunity to wear down their claws, dulling them andminimizing the damage that can be caused by the claws. The presentinvention seeks to capitalize on this natural and necessary activity ofcats by providing an abrasive surface on the bottom and or sides of alitter box so that a cat's claws will be dulled automatically when thecat uses the litter box. This eliminates the need to trim or manicurethe cat's claws or to have them surgically removed.

Extensive research and experimentation has been conducted by theinventor to determine the feasibility and best mode of the invention.One way of providing the abrasive material on the interior surfaces of alitter box is to incorporate the abrasive material into the injectionmolding process during manufacture. Research indicated that thisapproach is technically feasible but would be expensive because of theextreme wear to the injector caused by the abrasive material.Alternatively, an abrasive material can be directly applied to theinterior surfaces of a litter box, such as by spraying or rolling. Thisapproach is also technically feasible but presents environmentalproblems due to the extreme volatility of the adhesives used. Thepreferred way of providing the abrasive material on the interior surfaceof the litter box is to adhere an abrasive sheet material to the sidesand or bottom of an existing litter box. During experimentation,different combinations of abrasive materials, adhesives, and substratematerials were adhered to the inside surfaces of litter boxes and thecondition of the claws, as well as the behavior, of the cats using theselitter boxes was observed over a period of time. In this way it wasdiscovered that unless the adhesive was tasteless and odorless uponsetting, the cats refused to use the litter box. Due to their sensitivesense of smell, the cats were repelled by the odor of the adhesive. Itwas also observed that some cats would chew on the material, thusmandating that the adhesive be non-toxic to mammals. In this way it wasalso determined that sand paper was not suitable for use as the abrasivematerial, at least on the bottom of the box, because the paper was tooporous and not sufficiently resistant to cat urine, in extreme odor andmildew problems. In fact, the inventor was unable to find anycommercially available abrasive sheet material suitable to thisapplication. Therefor, the inventor developed the abrasive sheetmaterial, which will be described in detail below, specifically forapplication to the inside of a litter box.

The effect on the cats of various degrees of coarseness of the abrasivematerial was also observed. It was discovered that if the abrasive weretoo rough or course, the cat did not fully follow through on it'sscratching/litter covering pattern, whereby the necessary wear to theclaws was not obtained. If the abrasive were too fine, the claws werenot sufficiently dulled. In this manner, it was determined that anabrasive surface with a 240 to 320 grit was smooth enough to allow thecat to fully follow through on it's scratching/litter covering patternbut still course enough to significantly dull the claws. Theexperimental results also indicated that the smoother feel on the sidepanels was particularly important with respect to follow through becauseof weight displacement; that is, most of the cat's weight is outside thebox while one claw is in motion when the side panel is scratched.Therefor, it was determined that, in the preferred embodiment, the sidepanels are to be approximately 320 grit and the bottom is to beapproximately 240 grit.

The present invention takes the form of a sheet or sheets of materialhaving an abrasive coating on one surface and an adhesive on the othersurface so that the sheets of material can be adhered to the interior ofa litter box and the abrasive coating will wear down the claws of a catwhich uses the litter box. Preferably, the sheet of material is cut tofit the litter box and comprises five pieces shaped to line the sidesand bottom of the box.

The abrasive material is applied to a durable, flexible plastic basethat makes it easy to apply the sheet material on the inner surfaces ofthe litter box. The abrasive sheet material can be manufactured and soldas a single sheet which can be cut by the user to fit a particularlitter box or, preferably, the abrasive sheet material is produced invarious sizes applicable to a variety of litter boxes and packaged andsold in kit form containing four side panels and a bottom panel. As theterm is used herein, a "panel" refers to a piece of abrasive sheetmaterial which has been sized to fit on or is adhered on one of theinterior surfaces of a litter box. Alternatively, the sheet material isapplied to the interior surfaces of litter boxes during or immediatelyafter manufacture of the boxes and the boxes are packaged and sold withthe panels in place. The substrate material is preferably polyethyleneterephthalate, referred to as PET for convenience. The substratematerial may have a decorative pattern imprinted on it for changing theappearance of the box. The adhesive may be of the type which will allowthe panels to be easily removed whereby the user can replace the panelswhen worn or change to a different decorative pattern. Alternatively,the adhesive may be of the type whereby the panels are permanentlyattached to the box. The permanent type adhesive is preferred when theboxes are packaged and sold with the panels already attached. Theabrasive is preferably an environmentally safe abrasive material asapproved by the Environmental Protection Agency (EPA). Since the sidepanels will not be exposed to standing moisture (i.e., urine), a wet drypaper that carries the same non-toxic adhesive as the PET sheet and anEPA approved abrasive can be used.

In the preferred embodiment, an abrasive surface of aluminum oxidehaving a grit size of approximately 240 to 320 is formed on one surfaceof a thin sheet of PET. Aluminum oxide is the preferred abrasive becauseit is more environmentally sound than other alternatives such as silicondioxide products or flint in view of the airborne emissions which resultfrom scratching. In order for the thin PET or wet dry paper sheetmaterial to hold the aluminum oxide in place, a resin is applied overthe aluminum oxide. The resin is applied to one surface of thesubstrate, aluminum oxide abrasive is applied on the resin, and thenmore resin is applied over the aluminum oxide. This is called a resin onresin process. Other methods of affixing the abrasive to the substratecan be utilized as will be described hereafter. The resin may havewaterproofing characteristics to prevent the cat urine from penetratinginto the PET.

After the litter box is lined with the abrasive sheet, cat litter isadded into the box to a depth of approximately one and one-half inch.When a cat uses the litter box, the abrasive material, working withinthe bounds of nature, takes advantage of the instincts of the cat toscratch and claw in order to cover it's waste with litter. Thescratching and clawing will cause the claws to come into contact withthe abrasive surface, wearing and dulling the claws. In addition, theabrasive surface roughs the bottom of the cat pad thereby promotingsecretion of marking oils.

The adhesive may be chosen so as to allow the panels to be easilyreplaced without the necessity of replacing the litter box. The adhesiveis applied to the back of the sheet material and is covered by releasepaper. Thus, the panels can be changed when worn if the litter box isotherwise usable. Likewise, the cat owner can change the color orpattern of the abrasive surfaces at will. Such designs as cat paws,tiger stripes, leopards, or other suitable design may optionally beincorporated into the sheet material for cosmetic purposes. To apply theabrasive sheet material to the litter box, it is cut to fit the shape ofthe interior surfaces of the box, the release paper is peeled off andthe panels are fitted and adhered to the appropriate surfaces.Alternatively, the adhesive may be chosen to provide permanentattachment of the panels to the litter box. When permanent adhesive isused, it is preferable to attach the panels to the litter box during orimmediately after manufacture of the box and package the box with theabrasive surfaces as a finished product.

The above, and other novel features of the invention will be more fullyunderstood and appreciated from the following detailed description andthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prospective view of a litter box and an abrasive sheetmaterial being applied to the interior surface of the box.

FIG. 2 is a sectional view of the abrasive sheet material of theinvention.

FIG. 3 illustrates the fitting and application of the abrasive sheetmaterial to the interior of a litter box.

FIG. 4 shows a litter box containing absorbing litter and lined with theabrasive sheet material of the invention having decorative patterns.This figure also illustrates the action of a cat scratching the abrasivesurface on the bottom of the litter box.

FIG. 5 is a sectional view of a second, preferred embodiment of theabrasive sheet material of the invention.

DETAILED DESCRIPTION OF THE INVENTION

A litter box 10 suitable for use by domestic cats or other smalldomestic mammals is shown generally in FIG. 1. Such litter boxes areusually rectangular in shape and have sides 12 and 14, ends 16 and 18,and a flat bottom 20. They are designed to contain a scented absorbinglitter material as will be described in greater detail hereinafter. Whencats use the litter box they instinctively scratch in the box to covertheir waste. The present invention provides an abrasive sheet material22 that can be cut to fit the interior surfaces of litter box 10.Abrasive sheet material 22 has an abrasive material 24 on the uppersurface and an adhesive on the bottom surface temporarily covered byrelease paper 26.

In FIG. 1, the abrasive sheet material 22 is shown being applied tobottom 20 of litter box 10. Abrasive sheet material 22 is cut at end 28removing material 30 and cut at side 32 to remove material 34 to sizethe abrasive sheet material 22 to the proper size to fit on bottom 20 oflitter box 10. In some cases little or no sizing is required.Preferably, abrasive sheet material 22 is constructed to fit the largestsize litter box available and need only be trimmed to fit the bottomsurface of smaller boxes.

While a single sheet of abrasive sheet material can be applied to allinterior surfaces 12, 14, 16, 18, and 20 of litter box 10, it ispreferable to apply a separate sheet to each of the interior surfaces.This makes application of the abrasive sheet material easier, as asingle sheet would be difficult to fit into the corners, particularlywhen there is adhesive on it. Abrasive sheet material can be made largeenough to produce two cut end pieces 30 and two cut side pieces 34 withthe end and side pieces being large enough for application on theinterior of ends 16 and 18 and on the interior sides 12 and 14.Alternatively, the abrasive sheet material can be pre-cut in five piecesto fit a typical litter box and packaged and sold in kit form.Preprinted cut lines may be applied to the abrasive sheet material tosimplify installation.

Another advantage of separate sheets of abrasive material is thatindividual worn panels can be easily removed or replaced or differenttypes of abrasive sheet material, such as wet/dry paper, can be used forthe side and end surfaces than for the bottom surface. Still anotheradvantage is that a secure adhesive seal for each panel can be uniformlyachieved in spite of varying molding measurements of different litterboxes made by different manufacturers.

As previously mentioned, the abrasive sheet material may be permanentlyadhered to the interior surfaces of the litter boxes. This is especiallyadvantageous when the abrasive sheet material is applied prior to saleso that product being sold is a litter box with abrasive interiorsurfaces. One advantage is that the user does not have to cut up theabrasive sheet material or apply the abrasive sheet material him or herself. Thus, this form of the product is more convenient. Also, panelswhich are permanently adhered will not peel off or otherwise come offthe box prematurely. Also, panels put on the box by the manufacturer aremore likely to fit better, seal better and look better than thoseattached by the user. The disadvantage to this embodiment is that theentire box must be replaced when the abrasive material is worn orotherwise no longer effective.

One embodiment of the abrasive sheet material 22 to be placed on theinterior surfaces of litter box 10 is shown in FIG. 2. The base orsubstrate of the abrasive sheet material 22 is a thin, flexible plasticsheet material 36. The preferred material for the base or substrate 36is a 3 mil sheet of polyethylene terephthalate (PET) due to excellentstrength and chemical resistance in this application. Other flexibleplastic materials are suitable for use; for example, polymer filmmaterials such as polypropylene, cellulose acetate, polystyrene,polyvinylidene chloride (PVDC) can be used. Nylon or cellophane can alsobe used but tend to be more costly.

The upper surface of plastic sheet material 36 is covered with anabrasive material 24. The preferred abrasive has a grit size ofapproximately 240 to 320. The preferred process for affixing theabrasive to the substrate is the resin on resin process described above.As an alternative, the abrasive material can be produced by adding anabrasive to a resin and then applying it to the surface of plastic sheetmaterial 36 as a slurry coating. The abrasive is first wetted with anacceptable wetting agent such as a solvent. The abrasive is then addedto and thoroughly mixed with a suitable resin which prevents segregationand settling of the abrasive. As another alternative, the abrasive maybe applied to the substrate and the suitable resin is sprayed or rolledover the abrasive. The abrasive may be selected from common ceramicabrasives such as silicon carbide (SIC), aluminum oxide, commonly calledalumina (Al₂ O₃), zirconia (ZrO₂), zirconia alumina (ZrO₂ --AlO₃),garnet, and flint (SiO₂, silicon, quartz). Alumina is the preferredchoice for the abrasive because it is highly inert and very hard. It isalso very common, relatively inexpensive, and will not have any chemicalinteraction with a desired bonding resin. Other materials that can beused are include tripoly, emery and crocus for fine polishing. In thepreferred embodiment, the abrasive is alumina having a grit sizeapproximately 240 to 320.

The bonding resin may be selected from bonding materials such as rubber,shellac, a urethane such as polyurethane, epoxy, polyamide and otheralkyd resin bonds. Phenylformaldehyde (resinoid) compositions andvitrified (glassy) compositions can also be used to bond abrasives to asurface. However, the preferred material is a urethane. It is relativelyeasy to use, less expensive than other alternatives and will notinteract with the selected abrasive. The lower surface of sheet 36 iscovered by adhesive layer 38. A sheet of release paper 26 covers theadhesive layer 38.

A second embodiment of the abrasive sheet material is shown in FIG. 5,wherein a second sheet 50 of polyethylene terephthalate has it's uppersurface affixed to the lower surface of substrate 36 by a layer ofadhesive 38. In the preferred embodiment, this second sheet is 0.5 mil.The lower surface of second sheet 50 has a second layer of adhesive 52.Release paper 26 is shown covering second adhesive layer 52. In eitherembodiment, the adhesive may be a low tack adhesive which will providesufficient adhesion to securely hold the abrasive sheet material inplace in the litter box but still allow easy removal and replacementwhen desired by the user. Alternatively, the adhesive may be of the typeto provide a permanent attachment to the litter box surfaces. Apreferred adhesive for permanent attachment is a rubber based adhesive.Normally, although not necessarily, the adhesives 38 and 52 of FIG. 5will be the same for convenience of manufacture. The laminatedstructure, that is, the two sheets 32 and 50 being adhered together,provides a combination of flexibility and strength which would not beachieved with a single sheet thicker than 3 mil.

Although the sheet or sheets of polyethylene terephthalate and the resinprovide a water resistant barrier, a waterproofing treatment, such as awaterproofing silicon treatment, can be applied to further protect theabrasive sheet material from the effects of cat urine.

The abrasive sheet material can be sized to fit the largest of litterboxes or can be several sizes. These sizes range from a large jumbo sizebox of approximately 6.5 inches by 22 inches to a small size box ofapproximately 3.5 inches by 10 inches. With these dimensions, panels forsides 12, 14 and ends 16, 18 would be at least 6 inches high by about 24inches long. The panel to cover the bottom surface 20 is also sized tofit the largest litter box.

Attractive or decorative patterns 40, shown in FIGS. 3 and 4, can beincorporated into the abrasive sheet material. Polyethyleneterephthalate is very suitable for this purpose because it has highchemical and thermal stability, is very durable, has relatively lowthermal expansion, and has low shrinkage. It is easily coated withprinting inks as well as adhesives, exhibits high strength, hasexcellent tear resistance and is very moisture resistant and resistantto acids, bases, and solvents. If a pattern is desired, preferably thesubstrate or base sheet 36 is imprinted prior to being processed withresin, abrasive or adhesive. When used in the litter box, the patternedpanels will provide aesthetically pleasing decor in addition to thefunction of dulling the cat's claws.

Scents can be added to the abrasive sheet material to encouragescratching and act as a deodorant. The scent is added to the resin orimpregnated beneath the resin and abrasive layer. Scents known toattract cats or stimulate cats into wild and playful behavior, such asoil scents from catnip leaves, are suitable for this purpose. Although aportion of the scent will evaporate over time, some of the scentmaterial is trapped by a polymer chain or absorbed into the film orabrasive surface. The absorbed or trapped scent material will bereleased when the abrasive sheet material is scratched by the cat.

Application and use of the abrasive sheet material of the invention isshown in FIGS. 3 and 4. Each of the interior surfaces of the litter box10 is at least partially covered by removing release paper 36 andpressing each panel in place. FIG. 3 shows panel 22' being applied toside 14 of the litter box 10 already having panels applied to the otherside, the ends and the bottom. Side panel 22' is sized by cutting offpiece 42, the release paper 26 is removed and the adhesive surface ofthe panel is pressed against side 14. Thus, an attractive, scentedabrasive surface is provided on the interior surfaces of litter box 10.

FIG. 4 shows a cat scratching in a litter box whose interior surfacesinclude abrasive sheet material 22 and which is partly filled withabsorbent cat litter 44 to a depth of about one to one and one-halfinches. After depositing waste in the litter box, a cat will dig in thelitter 44 with paws 46, scratching the surface of abrasive sheetmaterial 22 with it's claws 48, thus wearing down the claws. Therecommended litter depth of about one to one and one-half inches is lessthan traditionally used in litter boxes which do not utilize the presentinvention. The decreased depth of litter increases the interaction ofthe cat's claws with the abrasive material on the bottom of the litterbox.

Although much of the above disclosure relates to the specificembodiment, especially the novel abrasive sheet material, for carryingout the present invention, it is to understood that the invention is notlimited by the embodiment shown in the drawings and described in thespecification but only in accordance with the scope of the accompanyingclaims.

What is claimed is:
 1. A litter box for domestic cats and other litterusing animals comprising:a container having interior side surfaces, endsurfaces and a bottom surface for holding cat litter; and, an abrasivemeans disposed on at least said bottom surface of the box for dullingthe claws of a cat or animal when the claws are scratched on saidabrasive means by the cat or animal when using the litter box, whereinsaid abrasive means comprises an abrasive sheet material adhered to atleast the bottom surface of the litter box, said abrasive sheet materialcomprising a first thin flexible substrate, an abrasive affixed to onesurface of the first substrate, a first adhesive on the other surface ofthe first substrate, a second thin flexible substrate having one surfaceadhered to said first substrate by the first adhesive, and a secondadhesive on the other surface of said second substrate, whereby theabrasive sheet material can be adhered to an interior surface of thelitter box by means of said second adhesive.
 2. The litter box of claim1 wherein said abrasive sheet material is disposed on the interior sidesurfaces, the interior end surfaces and the interior bottom surface ofthe litter box.
 3. The litter box of claim 3 wherein said first andsecond substrates are selected from the group consisting of polyethyleneterephthalate, polypropylene, cellulose acetate, polystyrene,polyvinylidene chloride, nylon and cellophane.
 4. The litter box ofclaim 3 wherein said first and second substrates are comprised of thesame material and said material is polyethylene terephthalate.
 5. Thelitter box of claim 4 wherein said first substrate has a thickness ofabout 3 mil and said second substrate has a thickness of about 0.5 mil.6. The litter box of claim 1 wherein said abrasive is selected from thegroup consisting of aluminum oxide, silicon carbide, zirconia, zirconiaalumina, garnet and flint.
 7. The litter box of claim 6 wherein saidabrasive is aluminum oxide.
 8. The litter box of claim 7 wherein thegrit size of said aluminum oxide abrasive is in the range of about 240to about 320 grit.
 9. The litter box of claim 2 wherein;said abrasive isaluminum oxide; the abrasive on the interior side and end surfaces has agrit size of about 320 grit; and, the abrasive on the interior bottomhas a grit size of about 240 grit.
 10. The litter box of claim 7 whereinsaid aluminum oxide abrasive is affixed to the substrate with a urethaneresin.
 11. The litter box of claim 1 wherein said second adhesive is ofthe type which allows removal of said abrasive sheet material from asurface of the litter box, whereby said abrasive sheet material can beselectively changed or replaced.
 12. The litter box of claim 1 whereinsaid second adhesive is a rubber based permanent type adhesive wherebythe abrasive sheet material is permanently adhered to the interiorsurface of the litter box.
 13. The litter box of claim 1 wherein saidabrasive sheet material includes a scent which is attractive to cats.14. The litter box of claim 1 wherein said abrasive sheet material has adesign, color, or pattern imprinted thereon.
 15. The litter box of claim1 wherein said abrasive sheet material includes a waterproofingmaterial.
 16. A litter box for domestic cats and other litter usinganimals comprising:a container having interior side surfaces, endsurfaces and a bottom surface for holding cat litter; and, an abrasivemeans disposed on at least said bottom surface of the box for dullingthe claws of a cat or animal when the claws are scratched on saidabrasive means by the cat or animal when using the litter box, whereinsaid abrasive means comprises an abrasive sheet material adhered to atleast the bottom surface of the litter box, said abrasive sheet materialcomprising a thin flexible substrate, an abrasive affixed to one surfaceof the substrate and an adhesive on the other surface of the substratefor adhering the abrasive sheet material to the surface of the litterbox, said abrasive being selected from the group consisting of aluminumoxide, silicon carbide, zirconia, zirconia alumina, garnet and flint,wherein the grit size of said abrasive is in the range of about 240 toabout 320 grit.
 17. The litter box of claim 16, wherein the abrasive isaluminum oxide.
 18. The litter box of claim 16, wherein said abrasivesheet material is disposed on the interior side surfaces, the interiorend surfaces and the interior bottom surface of the litter box.
 19. Thelitter box of claim 18, wherein said abrasive is aluminum oxide; theabrasive on the interior side and end surfaces has a grit size of about320 grit; and, the abrasive on the interior bottom has a grit size ofabout 240 grit.